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Writing disk images to 3.5" floppies with USB floppy drives

Our forum member Caius has yet again shared very valuable information for X68000 Compact owners.

Primarily in Japan there are 3,5“ floppy drives that support 3 modes of disk formats - 1.44MB, 1.25MB and 720kB. Hence the name “Floppy 3 mode”. The X68000 3.5” floppy drives spin at 360RPM and support 1.25MB but IBM PC 3.5“ drives at 300RPM and do not support 1.25MB format. That is why it is absolutely necessary to have a 3mode floppy drive. It is recommended to use USB models and Sony Vaio PCGA-UFD5 floppy drive was used for this test. It is very cheap and can be purchased from here:

Here is a list of some USB floppy drives with 3mode support:

  • IBM FD-05PUB (Teac OEM) - mode3 could be absent for models manufactured after 2005
  • Micropac technologies SBT-UFDB
  • Sabrent SBT-UFDB
  • Sony Vaio PCGA-UFD5
  • Toshiba PA3109U-1FDD
  • Panasonic CF-VFDU03

Here is a list of internal slim floppy drives with 3mode support:

  • Mitsumi D353F3 (Requires JM215A adapter for connecting to a regular PC)

Writing on DOS / Windows

Sadly Omniflop doesn't work with USB floppy drives so first you have to format correctly the 3.5 HD floppy with this DOS command:

  • format a: /a:1024 /t:77 /n:8 /u

or this one if the previous doesn't work:

  • format a: /fs:fat /v: /a:1024 /t:77 /n:8 /y

a: is the letter assignment to the floppy drive. It can change to b: or other, depending on your hardware configuration.

If you can't format a 3,5 floppy disk at 1.2 MB with these DOS commands, try this trick. First format the disk at 1.44 MB (using Windows utility) and then format it at 1.2 MB with the DOS command. Sometimes it can help.

After you have formated the 3.5 floppy disk, you can write back disk images using DiskImage 1.3b Utility:

DiskImage v1.3b

These are the correct settings:

  • FD mode option should be “1.25M”. Click on “HD→FD(125)” button to browse for *.xdf, *.dim or *.hdm files.
  • If you are using Windows Vista/7, use Windows XP mode for compatibility mode

Writing on Linux

You can do a low-level format of the floppy into 1.2MB mode with ufiformat:

  • ufiformat -f 1232 /dev/sdb

After that, disk images can be written as normal. XDF files are bare images, so you can write them with e.g. dd:

  • dd if=flop.xdf of=/dev/sdb

Writing disk images to 3.5" floppies with Greaseweazle / Fluxengine

3.5” floppies can also be written with USB flux imaging hardware. See writing_floppies for details.

x68000/writing_3.5_floppies.txt · Last modified: 2022/04/25 16:19 by TD-Linux